The disclosed embodiments relate to a medical device. Specifically, the disclosed embodiments relate to a junction structure for joining corresponding end portions of two tubular members, and a catheter having the junction structure.
A catheter to be inserted into a lumen in the body such as blood vessel, ureter, and the like of a patient at the time of procedure generally includes a tube member, a distal end tip joined to a distal end of the tube member, and a connector joined to a proximal end of the tube member.
Further, in such a catheter, the tube member is formed from multiple tubular members each having a different hardness. The tubular members are provided in series in order of decreasing hardness toward a distal end of the catheter in order to gradually increase the flexibility of the catheter toward its distal end.
For a tube member of a catheter manufactured by sequentially joining multiple tubular members as described above, the joined tubular members need to have sufficient joining strength to prevent the joined tubular members from detaching from each other even when the catheter is inserted into a body lumen of a patient and is bent along the curvature of the body lumen.
For example, Japanese Patent Application Laid-Open No. 2005-334542 describes medical tubes used for medical devices such as catheters, in which a joining area between the medical tubes is increased at each end of the medical tubes to enhance their joining strength when corresponding ends of the medical tubes are joined (see FIG. 1 and others).
However, in the medical tubes described in Japanese Patent Application Laid-Open No. 2005-334542, the joining strength is weak against a pressure in the radial direction. This may result in the following disadvantages: for example, when the medical tubes are joined via tapered portions formed at each end portion of the medical tubes (see FIG. 3(b)), the joined tapered portions are susceptible to forming cracks when the medical tubes are bent; and when the medical tubes are joined via stepped portions formed at each of the end portions (see FIG. 5), the joined stepped portions are also susceptible to forming cracks when the medical tubes are bent.